Currently, DSL services are normally offered as best effort services without any guarantees, e.g., with regard to end to end data rates (bandwidth) that will be provided. Such best effort services cannot support products that require certain specific guaranteed levels of bandwidth and/or quality of service (QoS) which may be expressed in terms of latency, jitter and/or packet loss. Products which require bandwidth and/or QoS guarantees include, for example VoIP, Video RT, or gaming. Products that require particular levels of guaranteed bandwidth and/or QoS guarantees are usually more expensive products then best effort products, e.g., basic Internet Access. Accordingly, DSL providers may increase their profits or increase the attractiveness of its offer in cases where they can provide a customer with various service guarantees.
Existing DSL architectures may control access and bandwidth based on ATM service classes but such implementations tend to be very expensive to implement and generally cannot be used ad-hoc or on request. In addition they are generally fixed type implementations that do not allow for flexible bandwidth allocation policies based on the particular user making the request in combination with the type of service being requested.
Providing bandwidth guarantees in a DSL network is complicated, particularly in the case of an existing system, by the difficulty to predict and/or control traffic on a network link. In existing DSL networks, portions of the networks often include traffic from outside sources, not under the control of the local service provider. These outside sources may inject traffic onto the local network consuming bandwidth. Given that the local service provider normally can not directly control such loads or know the actual load from such sources with certainty at any particular time, there is a need for taking such loads into consideration when deciding on whether to admit or deny requests for services.
In view of the above discussion, it should be appreciated that there is a need for load estimation methods for the links in DSL networks which could be used to efficiently estimate link utilization and control link utilization so that the capacity of each link in a network is utilized in an efficient manner.
Known approaches to varying user data rates include applying distributed load estimation methods. In such known methods, the admission control is distributed throughout the system, and decisions for a positive admission of a user to a higher level of service (e.g., more bandwidth) are evaluated by many elements (e.g., multiple routers, switches, DSLAMs, etc.) along the communications flow path. Each element performing an evaluation needs to give a positive decision for admission and/or more bandwidth allocation to a user. One such known method used to implement distributed load estimation involves RSVP (Resource Reservation Protocol). In the case of RSVP, the node to which each link along a communications path corresponds makes a separate determination as to whether the requested session will exceed link capacity. If any one node along a path determines it does not have the capacity to satisfy a session request, the request will be denied. Current implements of RSVP in DSL networks have been problematic and difficult to implement. Accordingly, there is a need for an alternative method to take into consideration link capacity and make admission control/service decisions based on available capacity.
In light of the above discussion, there is a need for improved methods of admission control and bandwidth allocation in communications networks, e.g., networks which provide different types of services over DSL and other types of lines to subscribers.
Methods of admission control and bandwidth allocation that utilize a centralized control method, as opposed to a distributed control method, could be beneficial. Methods that allow for users to request and relinquish various levels of premium (e.g., high bandwidth) services dynamically would be particularly desirable. It would be beneficial if at least some of the new methods allowed a user to dynamically terminate sessions/services to free up bandwidth need to satisfy a request by the user.